The present invention relates to apparatus for detecting and pinpointing localized changes in body temperature. More particularly, the invention relates to electrothermographic apparatus for detection and pinpointing or displaying of tumors, especially cancerous tumors in female breasts. Still more particularly, the invention relates to improvements in apparatus for monitoring selected portions of human bodies and for evaluating thermal radiation signals which are generated in the course of the monitoring operation.
It is known that the region of a malignancy in a human body develops temperatures exceeding those of the neighboring healthy tissue. The reason for such phenomenon is that a malignancy entails an increased localized tissue change activity which is promoted by increasing production of lymphatic and blood vessels. In the case of histologically confirmed malignant tumors, this leads to a rise of 1.degree.-7.degree. C. above the temperature of the neighboring or surrounding healthy tissue. In the case of benign changes of tissue, the temperature rise of the affected area is much less pronounced, normally less than 1.degree. C. As explained above, the number of blood vessels in a malignant tumor is greatly increased, i.e., the circulation of blood is much greater than in a healthy tissue with attendant rise of temperature of the affected portion of the body or an organ. The rise in temperature can be detected and localized with a reasonable degree of accuracy and sharpness.
It is also known to detect the presence or absence of malignancies in a human body by resorting to thermographic apparatus which monitor a selected portion of the body and generate signals denoting those spots or regions of the selected portion where the temperature deviates from the temperature of healthy tissue, and to utilize the results of such monitoring operation for pinpointing of actual or suspected malignancies. A presently known electrothermographic apparatus which is utilized for detection of malignant tumors comprises evaluating means in the form of a thermographic plate which contains liquid crystals. The plate records the temperature differences by changing the color or colors of one or more liquid crystals. The crystals are embedded in the plate and their color changes from red to green and thereupon to blue in response to increasing temperature. The temperature response is just the opposite (i.e., from blue to green and back to red) during cooling of the liquid crystals. It has been found that a thermographic plate can furnish reasonably sharp images of malignant and healthy areas, i.e., the outline of a malignant tumor can be seen with a relatively high degree of accuracy.
A drawback of apparatus which employ thermographic plates is that a plate must be brought into direct contact with the selected portion of the body. Therefore, the plate equalizes the temperatures of various spots or regions of the selected portion with attendant reduction of accuracy of the monitoring operation because the plate acts as a conductor of heat from warmer to cooler regions or spots. Moreover, it is not always possible to accurately conform the thermographic plate to the outline of the selected portion of a human body.